Abstract – We have studied hadronic events from e+e– annihilation data at different centre-of-mass energies .The operation of the AMY collaboration offers a unique opportunity to test QCD by considering different observables. The main results concern the measurement of the strong coupling constant, αs , from hadronic event shapes . The coupling constant, αs, is measured by two different methods, first by employing the jet clustering algorithm introduced by the JADE group. By using AMY data , the value of αs is determined to be 0.123± 0.004. Next, from the thee jet distribution, we extract the strong coupling constant, αs, at Leading(LO), Next to Leading(NLO) and Next to Next Leading Order (NNLO) from AMY data. The results are more consistent with the running of αs, expected from QCD predictions at NNLO corrections. We will discuss all these features in this paper. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved.

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